The Yingzaofashi [Building standards] is a Chinese building manual written by Li Jie (d. 1110) and published in 1103. I present a shape grammar for teaching the architectural style - the language of designs - described in this manual. This grammar is distinguished by two objectives, and the technical means used to accomplish them. First, the grammar is for teaching. Usually, the author of a grammar of a style aims to generate all and only the designs in the language. To do this, he not only writes the grammar, but also judges whether the designs it generates are members of the language. In the Yingzaofashi grammar, on the other hand, I want to generate all and more than the designs in the language. It is then the student who evaluates the designs - does this design belong to the language? - and adjusts the grammar accordingly. Thus the student participates actively in defining the language of designs, and learns that style is a human construct. Second, the grammar is designerly. As already observed, most authors of style grammars focus on the language of designs; they do not consider how to structure the user's interaction with the grammar. By contrast, I consider explicitly what the user decides and when he decides it, and organize the grammar accordingly. In other words, I consider process as well as products. The grammar exploits several technical devices for the first time: the design as an n-tuple of drawings, descriptions, and other elements; the generation of descriptions in the n-tuple; and techniques that are made possible by these devices.